CVE-2026-55778
Parse Server: Stored XSS via non-standard file extension bypassing file upload extension blocklist
CVSS Score
0.0
EPSS Score
0.4%
EPSS Percentile
33th
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.11 and 8.6.81, the default fileUpload.fileExtensions blocklist could be bypassed by uploading a file with a non-standard or compound extension and dangerous content type, allowing storage adapters such as S3 and GCS to serve attacker-supplied active content and enable stored cross-site scripting. This issue is fixed in versions 9.9.1-alpha.11 and 8.6.81.
| CWE | CWE-434 |
| Vendor | parse-community |
| Product | parse-server |
| Published | Jul 8, 2026 |
| Last Updated | Jul 9, 2026 |
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Affected Versions
parse-community / parse-server
>= 9.0.0-alpha.1, < 9.9.1-alpha.11 < 8.6.81
References
github.com: https://github.com/parse-community/parse-server/security/advisories/GHSA-v8x7-r927-cc93 github.com: https://github.com/parse-community/parse-server/pull/10505 github.com: https://github.com/parse-community/parse-server/pull/10506 github.com: https://github.com/parse-community/parse-server/commit/97c6a78d19f976ec756c1295f08a8fccab90799a github.com: https://github.com/parse-community/parse-server/commit/be12a60d65b6e140481882037fb896b1f951df50 github.com: https://github.com/parse-community/parse-server/releases/tag/8.6.81 github.com: https://github.com/parse-community/parse-server/releases/tag/9.9.1-alpha.11